By Subir Bhaumik
BBC News, Calcutta
Separatist rebels have shot dead a tea estate manager in India's north eastern state of Assam, jolting an uncertain peace process in the troubled state.
Indian forces have been on truce
The rebel attack comes a day after the government threatened to resume military operations in Assam.
India wants the outlawed United Liberation Front of Assam to join peace talks directly and not via mediators.
Military operations had been suspended in August in Assam, but the Indian army has been pressing to resume it.
Police said four rebels shot dead Haren Das, a manager of the Hailanga tea estate in front of his residence, not far from Assam's northern oil town of Digboi.
The rebels' strike late on Saturday followed reports that the ULFA was involved in large-scale extortion from Assam's more than 800 tea estates.
Oil and tea are the mainstay of Assam's economy and Assam is India's largest tea-producing state.
The peace process in Assam had suffered a setback on Friday when the Indian government said it would resume military operations against the ULFA unless the rebel leadership gave a written commitment to join the talks directly and not negotiate to a committee of Assamese civil society personalities, as they have done for nearly a year now.
But the rebels are insisting on the release of five of their top leaders now serving sentences in Indian prisons before they will join the talks directly.
The ULFA, formed in 1979 to fight for Assam's independence, had unleashed a series of explosions targeting oil and gas pipelines, railway tracks and road bridges, telecommunication facilities and security patrols this year until the Indian government stopped military operations against them last month.